CVE-2018-3761 Explained : Impact and Mitigation

CVE-2018-3761 was published on July 5, 2018, and affects Nextcloud Server versions prior to 12.0.8 and 13.0.3. The vulnerability lies in the OAuth2 token endpoint, making it susceptible to improper authentication.

Understanding CVE-2018-3761

This CVE highlights a security flaw in Nextcloud Server versions that could lead to the unauthorized distribution of new tokens.

What is CVE-2018-3761?

The vulnerability in CVE-2018-3761 allows for improper authentication on the OAuth2 token endpoint due to missing checks, potentially enabling the issuance of new tokens if the OAuth2 client is partially compromised.

The Impact of CVE-2018-3761

The vulnerability could result in unauthorized access to sensitive data and services, compromising the security and integrity of the affected systems.

Technical Details of CVE-2018-3761

CVE-2018-3761 involves the following technical aspects:

Vulnerability Description

The OAuth2 token endpoint in Nextcloud Server versions prior to 12.0.8 and 13.0.3 is vulnerable to improper authentication, allowing the potential distribution of new tokens in case of partial compromise of the OAuth2 client.

Affected Systems and Versions

Product: Nextcloud Server
Vendor: Nextcloud
Vulnerable Versions: <13.0.3, <12.0.8

Exploitation Mechanism

The absence of appropriate checks in the OAuth2 token endpoint facilitates the exploitation of this vulnerability, leading to the unauthorized issuance of new tokens.

Mitigation and Prevention

To address CVE-2018-3761, consider the following mitigation strategies:

Immediate Steps to Take

Update Nextcloud Server to version 12.0.8 or 13.0.3 to eliminate the vulnerability.
Monitor and restrict access to the OAuth2 token endpoint.

Long-Term Security Practices

Implement multi-factor authentication to enhance access control.
Regularly audit and review OAuth2 client configurations for security gaps.

Patching and Updates

Stay informed about security advisories from Nextcloud and promptly apply patches to secure the system against known vulnerabilities.